Heretofore the manufacture of sauce pans and similar cookware has required a substantial amount of labor because each of the several steps in the manufacturing operation was performed by a different machine, and workpieces had to be transported from machine to machine and manually fed into each machine and removed from it.
Typically, the manufacture of an aluminum sauce pan body starts with a flat disc that is inserted into a heavy press to be formed into a more or less cup-shaped blank having a bottom wall, an upright substantially cylindrical side wall, and a rim around the top of its side wall that projects either upwardly or radially outwardly. Usually the production of this blank requires successive forming operations whereby the blank is progressively deepened.
The blank thus produced must be subjected to certain finishing operations that require it to be rotated in engagement with a tool, and to certain other finishing operations during which it remains stationary.
Especially in the case of an aluminum piece, the outer surface of the unfinished blank has a roughness sometimes referred to as "orange peel" that is removed by rotating the blank while forcefully engaging it with an axially moving smoothing tool. The flange-like rim around the top of the blank has an irregular edge and must be trimmed to a uniform width by means of a cutting tool that also engages the blank while it is rotating. After it is trimmed this flange is usually reformed in some manner, as by folding or curling it downward to produce a bead or the like around the top edge of the vessel, and, again, such reforming is accomplished by means of a tool that engages the piece while it is rotating. There are other possible operations that may be performed while the blank rotates, such as the formation of shallow ornamental grooves in the outer surface of its side wall.
The finishing operations that may be performed while the piece is stationary include piercing its side wall with a hole or holes for handle attachment, stamping a trademark or the like on the underside of the bottom wall, and panelling the bottom wall, that is, upwardly offsetting its central portion to prevent the pan from rocking when heated.
Heretofore these finishing operations have required a substantial amount of hand labor, performed with at least two machines. For its rotation, the blank was manually inserted into a chuck and manually removed from it. Once the blank was chucked and rotating, the several tools that performed the finishing operations could be engaged against it automatically, but the machine nevertheless required the substantially constant presence of an attendant who chucked and removed the workpieces. The finishing operations that were performed with the blank stationary were accomplished at a machine that likewise required substantially constant attendance for insertion and removal of workpieces.
The amount of labor required for production of cookware has had some tendency to place American manufacturers at a competitive disadvantage with manufacturers in foreign countries where labor is cheap. Until recent years, however, American cookware manufacturers had not suffered unduly from foreign competition because manufacturers in countries with very cheap labor had been unwilling or unable to invest in the heavy, expensive blanking presses and other machines needed for cookware manufacture.
In the last few years the competitive situation has changed to the marked disadvantage of American manufacturers, owing to the introduction of a style of cookware which has become very popular and which has heretofore been regarded as suitable only for low capital, labor intensive production. Such cookware is characterized by an enlarged diameter bulged bottom portion on the body of the vessel. The blank for such a vessel has heretofore been produced by a spinning operation that can be performed with simple and inexpensive machinery but requires a substantial amount of labor. Understandably, most of the cookware of that style has been imported into the United States from countries that have abundant low cost labor, and because of its popularity, it has cut into the sale of American-made cookware.
While it is technically possible to employ a press for imparting a bulge to the bottom portion of a blank initially formed with a substantially cylindrical side walk, the presses heretofore available that would have been capable of such work were very expensive. Interest and amortization costs on the high capital investment in such a press, plus the cost of labor for loading and unloading it one piece at a time, would have precluded economically feasible competition with imported products.
The need for automating the production of cookware, and particularly for automating the finishing operations, has been apparent for a long time. Heretofore, however, those skilled in the art have not known how to accomplish such automation. Particularly baffling has been the problem of automating the finishing operations that require rotation of the workpiece, owing to the complex manipulations considered necessary for chucking and unchucking the workpiece. The blank has to be brought into proximity to the chuck without conflict with the tools intended to engage the workpiece, it has to be centered relative to the chuck, the chuck has to be closed while the workpiece is held in a proper position and orientation, and subsequently the chuck has to be opened and the workpiece removed from it, again without conflict with the tools.
Reasonable efficiency requires that the workpiece be transported mechanically to and from each of at least two finishing stations, at one of which the workpiece is rotated and at the other of which it is maintained stationary. Heretofore it was by no means obvious how a simple, inexpensive and fast acting conveyor could effect the necessary transport of workpieces, considering that the conveyor must establish each workpiece at the proper location and orientation at each station but must nevertheless be so arranged that both it and the workpieces remain clear of the instrumentalities that operate on the workpiece at each station.